1. Field of the Invention
The present invention relates to a crank for a bicycle and a method for manufacturing the same, and specifically, to a crank for a bicycle formed by bonding structural members to each other with an adhesive intervening therebetween and a method for manufacturing the same.
2. Description of Related Art
A crank for a bicycle is frequently formed from members each having a relatively complicated three-dimensional shape which has a curved-surface portion or a rising-wall portion, and when a fiber reinforced plastic (hereinafter, abbreviated as “FRP”) is used as a material for weight-saving and the like, structural members of FRP members or an FRP member and another material member are frequently bonded to each other by using an adhesive. In a conventional technology, when the structural members are bonded to each other with an adhesive, for example, the adhesive is applied to a bonding portion of one of the members, the other member is assembled with the member applied with the adhesive, and the structural members are bonded to each other with the adhesive intervening therebetween.
Because the structural member to be applied with an adhesive has a relatively complicated three-dimensional shape which has a curved-surface portion or a rising-wall portion, as described above, application of such adhesive is usually carried out by manual operation. Because adhesive is applied by manual operation, more or less a variation of application condition or a variation of amount of used adhesive (application amount) occurs, and ascribed thereto, a variation in quality such as bonding strength or a variation in product weight may occur. Although it is considered to use a robot for application of adhesive, in practice, there are many cases where desired application of adhesive to a complicated curved-surface portion, an undercut portion, etc. is difficult, and even if such application of adhesive is possible, introducing such a robot for a bonding process results in very expensive equipment cost.